1. Field of the Invention
The present invention relates to an information transmitting apparatus and method, an information receiving apparatus and method, a provider, and a broadcasting system. In particular, the invention relates to an information transmitting apparatus and method, an information receiving apparatus and method, a provider, and a broadcasting system in which the transmission amount of data of program information can be increased when the transmission amounts of video data and audio data can be decreased. The invention also relates to an information transmitting apparatus and method, an information receiving apparatus and method, a provider, and a broadcasting system in which the information receiving apparatus can recognize, in a short time, the transmission statuses of schedule EPG data that indicate program broadcast schedules of the transmission side.
2. Description of the Related Art
In digital broadcasting systems, EPG (electronic program guide) data for providing program information is formed in an EIT (event information table) format according to the rules of DVB/SI (Digital Video Broadcasting/service Information: EN300468) and multiplexed with other services information (SI) into a transport stream.
FIG. 1 is a table showing an example of the EIT in which the total transmission rate of EPG information is set at 150 kbps. The EIT consists of a network ID, a TS-ID, a service ID, table IDs, program broadcast hours corresponding to the table IDs, program lengths corresponding to the table IDs, and other data. Further, a program title, genre information, etc. can be described in descriptors together with a broadcast start hour and a program length.
The EIT generally consists of EPG data of the self station and EPG data of other stations, each of which consists of data of current and next programs, data of programs within 6 hours from the present time, data of programs that are 6-24 hours away, data of programs that are 2-3 days away, and data of programs that are 4-8 days away. The data of programs within 6 hours from the present time, the data of programs that are 6-24 hours away, the data of programs that are 2-3 days away, and the data of programs that are 4-8 days away are generically called schedule EPG data that indicates a program broadcast schedule. Each of those EPG data has its own Table_id (Table_identification code) and a re-transmission cycle. EPG data are transmitted at re-transmission cycles that are set for the respective Table_id data and have respective prescribed transmission rates. The EPG data of current and next programs has a relatively short re-transmission cycle of about several seconds. On the other hand, the schedule EPG data indicating a program broadcast schedule has a re-transmission cycle of about several minutes, which is longer than the re-transmission cycle of the EPG data of current and next programs.
As shown in FIG. 2, as for the transmission of EPG data, a prescribed EPG data (including prescribed services information) occupation bandwidth is set for the transmission channel bandwidth of a digital broadcasting system. Since priority is given to the transmission of video data and audio data, the EPG data occupation bandwidth does not vary even if a free portion occurs in the occupation bandwidth for the transmission of video data or the occupation bandwidth for the transmission of audio data.
A viewer takes long time to acquire program information when the data amount of EPG data is large, because EPG data is transmitted to an information receiving apparatus at a constant transmission rate even if a free portion occurs in the occupation bandwidths for the transmission of video data and audio data.
Further, since schedule EPG data indicating program broadcast schedules has long re-transmission cycles and there is no data indicating their transmission statuses, an information receiving apparatus takes long time to judge the state of the transmission side when the transmission of the schedule EPG data is suspended due to the equipment trouble on the transmission side.